When to Plant Kabocha in Grundy County, IL
Kabocha is a Japanese winter squash with an exceptionally sweet, dense, chestnut-like flesh and dark green skin. It is a favorite in Asian cuisine for its rich, dry texture.
Grundy County, Illinois is in USDA Zone 5a. The average last spring frost is April 20 and the first fall frost is October 17, giving you a growing season of approximately 180 days.
At an elevation of 629 feet, Grundy County receives approximately 30.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Kabocha during the growing season.
Grundy County Soil Profile
Soil Type
Silt Loam
Soil pH
6.1-7
Drainage
Well Drained
Plant Planting Risk Windows
Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Kabocha Planting Timeline — Grundy County, IL
Kabocha Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 16 | Mar 16 – Mar 30 |
| Transplant Outdoors | May 4 | May 4 – May 18 |
| Direct Sow | April 27 | Apr 27 – May 18 |
| Harvest | August 3 | Aug 3 – Aug 31 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | — |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Moderate — regular watering
Days to Maturity
85–100 days
Soil pH
6 – 7.5
USDA Zone
Zone 5a
Growing Season
180 days
Growing Tips for Grundy County
Direct sow after frost or start indoors. Harvest when the skin is hard and dull. The stem should be dry and corky. Stores well for 3-4 months in a cool, dry place.
Companion Planting
Good Companions
Avoid Planting Near
Level Up Your Garden
Kabocha in Other Locations
Frequently Asked Questions
When should I plant Kabocha in Grundy County, IL?
Grundy County is in Zone 5a with an average last frost of April 20. Plan your Kabocha planting based on this frost date — see the calendar above for exact timing.
What planting zone is Grundy County, IL?
Grundy County, Illinois is in USDA Hardiness Zone 5a. The average last spring frost is April 20 and first fall frost is October 17.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Grundy County gardeners in Zone 5a organize planting dates, track what's growing, and never miss a planting window.
Get Your Free Garden Planner →Free download. Plan your entire garden season in minutes.